Measurement and Performance Analysis of Pneumatic Braking Systems on Heavy Vehicles

摘要

Heavy commercial vehicles account for a large percentage of vehicles operating on public roadways, and an even larger percentage of vehicle miles traveled. The pneumatic braking system which heavy vehicles are equipped with, is often found to be deficient by law enforcement and investigators during roadside inspections or following a collision. Deficient pneumatic braking systems increase the distance necessary for a fully laden heavy vehicle to slow or stop. The stopping distance of a heavy vehicle, even when the braking system is fully functional, is significantly longer than that of a passenger vehicle. Slow deceleration rates and long stopping distance can, and do, result in collisions. The licensed commercial driver of a heavy vehicle is federally mandated to complete pre-trip inspections. These pre-trip inspections, and inspections completed by maintenance personal during the servicing of the vehicle, are often inadequate and may fail to identify burgeoning problems within the vehicle's braking system. Current technology in heavy vehicle braking systems lessens the burden on the driver to constantly maintain the braking system, but does not eliminate the need for regular inspections, and maintenance if needed. Even with current technology, it remains common to find the adjustment of the braking system components on over-the-road heavy vehicles beyond safe limits during roadside inspections.;This project presents an overview of the mechanical function of the modern S-cam pneumatic braking system commonly found on heavy vehicles in the United States. The areas of failures and potential deficiencies within S-cam pneumatic brakes is explored and discussed. Additionally, several different pneumatic braking performance analysis methods are presented, which can be used to determine the maximum deceleration rate and speed of a heavy vehicle with a fully operational braking system, and when the braking system is compromised. Examples of each analysis method are included in appendices to this paper.;This project presents research examining the potential use of an ultrasonic sensor to, in real-time, measure and relay the adjustment of a heavy vehicle's brakes to the operator of the vehicle. In this way the operator of the vehicle will be alerted when the adjustment limit of a brake on their vehicle or trailer(s) is reached. Additionally, an alternative design for the studied sensor, which would fulfill the same purpose, is presented in detail.